This invention pertains to can bodymaking, and especially to machines for side-seam soldering.
In view of the increased costs of tin plate, solder, and can-making labor, manufacturers are seeking to reduce the already low losses due to spoilage. One serious problem in connection with the side-seam soldering practice presently prevailing is that the can bodies when formed with side-seams to be soldered are not positively maintained in proper uniform orientation. This is to say that at production rates of 500/ minute or so, as the bodies progress in currently available soldering machines (for instance of the type disclosed in U.S. Pat. No. 3,000,338), the interlocking side lap joints or seams of the bodies commonly passing from a stub horn to a solder applicator and thence to mechanism such as a body end lap depressor chain for minimizing joint thickness, an occasional can body side seam may deviate from alignment and/or orientation about a longitudinal axis. As a consequence weak seams will be produced in the aberrant bodies as a result of solder not being deposited entirely in their side seam openings.
In U.S. Pat. No. 3,056,368 issued in my name, for example, there is disclosed a can body conveying chain and guide members positioned close thereto and externally of the bodies so as to compress the successive circular bodies into elliptoidal cross sections wherein their major axes are generally horizontally disposed. A further approach to maintaining seam alignment integrity in a body-soldering machine while also accommodating variation in can body dimensions is disclosed in U.S. Pat. No. 3,255,856 issued in my name, guide rods being shown therein as having yieldable contact with the exteriors of the bodies. Also, in the prior art it is known to employ expensive ceramic V-guide rails for guiding can bodies, and to use so-called "solder-horses", i.e. a cage-like construction comprising tubes bearing externally on the bodies as they are conveyed. The mentioned variants, so far as known, have not provided a uniformly straight and sufficiently controlled guidance of the can body seams.